Signal recording and reproducing apparatus

ABSTRACT

A signal recording and reproducing apparatus where the signal is recorded in a forward and reverse direction on a magnetic medium such as tape and where the signal to be recorded is supplied to the recording head through a delay circuit with a delay between the recording head and the magnetic tape in the second direction being larger than the signal delay between the head and the tape in the first direction and wherein the difference between these two delays is longer than the time required for tape reversal.

This is a continuation of application Ser. No. 705,333, filed Feb. 12,1985, now abandoned.

TECHNICAL FIELD

This invention relates to a signal recording and reproducing apparatusfor recording audio or video signals on a recording medium such asmagnetic tape and for reciprocatingly reproducing the recording and,more particularly, to a signal recording and reproducing apparatus inwhich the direction in which the tape runs during recording orreproduction, can be automatically reversed.

BACKGROUND ART

With a auto-reverse type audio tape recorder, that is, a tape recorderin which the terminal tape portion (tape end) is sensed during recordingor reproduction for automatically reversing the tape running direction,the recording or reproduction may be interrupted during the reversalperiod resulting in the omission of a sound during such time. Since themechanical operation is involved during the reversing of the rotationaldirection of the capstan, it is extremely difficult to lower the timerequired for such reversal to less than 0.1 second, even if the recorderis provided with a fast reverse mechanism. This may cause problemsespecially when recording and reproducing digital signals obtained bypulse code modulation of the audio signals. In such case, a signalomission over 0.1 second gives rise to an insufficient error correctingfunction and results in the inability to perform high qualityreproduction with the possibility of abnormal sounds occurring.

The present invention contemplates providing a signal recording andreproducing apparatus whereby auto-reverse recording and reproductionare effected without signal omission so as to obtaintemporarily-continuous playback signals.

DISCLOSURE OF THE INVENTION

The feature of the signal recording apparatus resides in the signalrecording apparatus wherein, after at least one of the recording headand the recording medium has made relative movement relative to theother in a first direction, it is moved in a second direction oppositeto said first direction for reciprocatingly recording input signals onsaid recording medium, wherein, according to the invention, means areprovided for supplying said input signals to said recording head with adelay, and the amount of delay quantity in the input signals duringrunning in said second direction is set to be longer than the delay inthe input signals during running in said first direction, and thedifference between these delays is set to be longer than the timerequired for the tape reversal from said first direction to said seconddirection.

The feature of the signal recording and reproducing apparatus accordingto the present invention resides in apparatus wherein, after at leastone of the recording head and the recording medium has relative movementrelative to the other in a first direction, it is moved in a seconddirection opposite to said first direction so as to reciprocatinglyrecording input signals, and the thus reciprocatingly recorded recordingmedium is caused to travel in said first and second directions forreproducing the recording with a reproducing head, wherein, according tothe invention, during recording, means are provided for supplying saidinput signals to said recording head with a delay, and the delay in theinput signals during running in said second direction is set to belonger than the delay in the input signals during running in said firstdirection and the difference the delay is set so as to be longer thanthe time required for the tape reversal from said first direction tosaid second direction. During reproduction, means are provided fordelaying the reproduced signals from said reproducing head, with thedelay of the reproduced signal prior to the movement reversal being setto be longer than the delay of the reproduced signal after the movementreversal, and the output from said delay means is removed assubstantially continuous signals.

The feature of the signal recording apparatus according to the presentinvention is that input signals are reciprocatingly recorded on therecording medium, and, according to the invention, reversal markingsignals indicative of the reversal are recorded on said recording mediumin the vicinity of the reversal position along with said input signals.

In addition thereto, the feature of the signal recording and reproducingapparatus according to the present invention, is that, the input signalsand the addresses corresponding thereto are reciprocatingly recorded ona recording medium and, the thus recorded signals are read out in boththe forward and return directions during forward reproduction andwherein the thus read out forward direction addresses and returndirection addresses are compared to each other for determining themovement reversal position from the forward reproduction to the returnreproduction.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block circuit diagram showing the basic construction of therecording part of the signal recording and reproducing apparatus of thepresent invention;

FIG. 2 is a plan view showing an example of the recording pattern on themagnetic tape;

FIG. 3 is a chart showing changes in the forward direction addresses andthe return direction addresses relative to the amount of tape travel;

FIG. 4 is a block circuit diagram showing the basic construction of thereproducing part of the signal recording and reproducing apparatus ofthe present invention;

FIG. 5 is a block circuit diagram showing an example of the constructionof the signal recording part for explaining an embodiment of theinvention;

FIG. 6 is a diagram showing an example of the block format of therecorded signal;

FIGS. 7 to 9 are views for explaining address changes in the signaldelaying RAM shown in FIG. 5;

FIG. 10 is a block circuit diagram for explaining an embodiment of thepresent invention;

FIGS. 11 to 13 are views for explaining address changes in the signaldelaying RAM shown in FIG. 10; and

FIG. 14 is a plan view showing an example of the recording pattern onthe magnetic tape for explaining a further embodiment of the presentinvention.

BEST MODE FOR EXECUTING THE INVENTION

The signal recording and reproducing apparatus of the present inventionis now described.

FIG. 1 is a block diagram for explaining the operating principle of therecording part of the signal recording and reproducing apparatus. InFIG. 1, audio, video or other common data signals are supplied to aninput terminal 1 in a digital signal format. These input signals aresupplied to a selected first terminal a of a changeover switch 2, andare also supplied to a selected second terminal b of the switch 2through a delay element 3 consisting of a memory such as shift registeror random access memory (RAM). The output from the changeover switch 2is supplied through a recording amplifier 4 to a recording head 5 so asto be recorded on a recording medium such as a magnetic tape 6. The tape6 is caused to run in a first direction relative to the magnetic head 5,e.g. in the direction shown by the arrow A. When the tape has reachedthe tape end position, for example, the tape is caused to run in asecond direction opposite to the first direction, e.g. in the directionshown by the arrow B. The changeover switch 2 is set to the selectedfirst terminal a when the tape 6 runs in the first direction or thedirection shown by the arrow A and to the selected second terminal bwhen the tape 6 runs in the second direction or the direction shown bythe arrow B. It should be noted that the element 3 has a delay timeT_(D) longer than the time T_(R) required for reversing the movement ofthe tape 6 from the first direction to the second direction (time ofmovement reversal) so that the signal appearing at the magnetic head 5immediately after such movement reversal temporarily precedes the inputsignal immediately before the movement reversal. When the input signalis an analog signal on, analog delay element such as a bucket brigadedevice (BBD) or charge coupled device (CCD) may be used as theaforementioned delay element 3.

The recording pattern on the magnetic tape 6 at the time of recordingaccompanying such movement reversal is shown for example in FIG. 2. InFIG. 2, the two recording tracks 7A, 7B on the magnetic tape 6 areformed in accordance with the recording in the aforementioned first andsecond directions (forward and return directions) in such a manner thatthe track 7A is formed when the tape 6 runs in the first direction (inthe direction of the arrow A) relative to the recording head 5, and thetrack 7B is formed when the tape 6 runs in the second direction (in thedirection of the arrow B). When the tape 6 is assumed to remainstationary, the head 5 has a relative movement thereto in oppositedirections, i.e. in the directions shown by the arrows A or B. In FIG.2, the numbers entered in the tracks 7A, 7B represent the numbers (oraddresses) of temporarily consecutive blocks of the input signals, andthe right side extreme portions of the tracks 7A, 7B represent invalidrecord portions corresponding to tape acceleration or decelerationduring movement reversal.

It is assumed that, with one block time (block period) T_(B) on the timeaxis, the time T_(R) required for movement reversal is equal to fourblocks time 4 T_(B), whereas the delay time T_(D) of the delay element 3is equal to eight blocks time 8 T_(B).

In such case, the input signal supplied to the input terminal 1 appearsdirectly (i.e. with zero delay time) at the terminal a of the changeoverswitch 2 of FIG. 1, whereas the input signal delayed by eight blockstime 8 T_(B) appears at the terminals b of the change-over switch 2.When the tape 6 runs in the first direction A (forward direction) theswitch 2 has been set to the terminal a so that the input signal isdelivered directly to the magnetic transducer head 5 and is sequentiallyrecorded on the first recording track 7A of the magnetic tape 6.Supposing that the tape has reached the terminal position at the timewhen the 15th block has been recorded, an automatic movement reversaltakes place during the time interval T_(R) (=4 T_(B)) and the tapestarts to run in the second direction B. At this time, the switch 2 isset to the terminal b and the signal corresponding to the input signaldelayed by T_(D) (=8 T_(B)) is delivered to the head 5 and issequentially recorded on the second track 7B of the tap 6. The inputsignal supplied to the input terminal 1 immediately after such movementreversal is the 19th block signal which is delayed by 4 T_(B) from the15th block appearing immediately before the movement reversal. However,the output signal from the delay element 3 is the 11th block signalwhich is earlier by eight blocks (8 T_(B)) so that the signals aresequentially recorded on the second recording track 7B of the tape 6starting from the 12th block. Thus the four blocks from the 12th to the15th blocks are doubly or redundantly recorded before and after themovement reversal so as to prevent signal omissions. It is possible toset the delay time T_(D) of the delay element so as to be equal to thetime T_(R) required for movement reversal (T_(D) =T_(R)) for preventingsignal omission. However it is desirable to set the delay time to begreater than the time required for movement reversal T_(R) (T_(D)>T_(R)) and to utilize the time difference T_(D) -T_(R) as a time marginor allowance while considering that fluctuations may be caused duringthe time required for reversal and in the reversal position because ofthe mechanical means used for effecting the movement reversal and errorscaused in tape end detection.

Although the signal delay is effected in the embodiment of FIG. 1 onlyfor the recording in the second direction, it is also possible that asimilar delay of the input signals be introduced for recording in thefirst direction. For example, with a signal delay time T_(DA) for therecording in the first direction and with a signal delay time T_(DB) forrecording in the second direction, if the delay time intervals T_(DA),T_(DB) are set so that the time T_(D) is equal to the difference betweenthese delay intervals or the time T_(DB) -T_(DA) is longer than the timerequired for movement reversal T_(R) (T_(D) =T_(DB) =T_(DA) >T_(R)),recording without omission of input signals can be achieved.

When the signal delay time intervals are switched between the recordingin the first direction and that in the second direction, it is notnecessary to effect switching between the two signal delay elementsusing hardware. For example, it is sufficient that a delay element suchas a random access memory (RAM) be provided and the difference betweenthe write and read addresses for recording in the first direction is setso as to be different from that for the recording in the seconddirection in order to provide for the different signal delay times inwriting and reading to and from the RAM.

In general, when signals to be recorded are the digital signals obtainedby pulse code modulation of the sampled values of the audio or videosignals, delay elements such as memories are already employed for signalprocessing such as for word interleaving or for error correction coding.In such cases, it is more practical that these memories which are usedfor signal processing (e.g. encoding) be used simultaneously as thesignal delay element 3 during the above described tape reversal.Although the delay elements 3 are included in the signal processingcircuit, it is of course possible that the delay elements be providedahead of or in back of the encoder.

The recording tracks 7A, 7B of the patterns shown in FIG. 2 are formedon the magnetic tape 6 by the signal recording process described in theforegoing. When the thus recorded magnetic tape 6 is reciprocatinglyreproduced by an automatic movement reversal (auto-reverse), andassuming that the tape is reversed after recording up to the 15th blockin the first direction, the 12th to 15th blocks will be reproducedredundantly (will be produced twice) during reproduction in the seconddirection, which means an increased signal delay memory capacity.

Thus, with the signal recording and reproduction apparatus of thepresent invention, not only the block addresses for the first directionbut those for the second direction are read out during reproduction inthe first direction and the block addresses for the first and seconddirections are compared for deciding the optimum reversal position.

Thus, when the tape is running in the first direction A for reproductionin the forward direction each block address for the forward and reversedirections are changed with direction which the tape runs in the manneras indicated in FIG. 3. In FIG. 3, the forward direction addressesindicated by the solid line are incremented while the return directionaddresses are decremented with increase in the amount of tape travel.The tape running position X immediately after the forward directionaddresses and the return direction addresses are the same. The Xposition comprises an optimum running reversal position and provides forgood reproduction of the recorded signal data without omissions and alsoprovides for a minimum delay memory capacity.

The basic construction for effecting automatic tape movement reversalduring reproduction is shown by way of an example in FIG. 4. In FIG. 4,the recording track 7A of the magnetic tape 6 recorded by the abovedescribed recording method is reproduced by a forward reproducing head21A, and the recording track 7B is reproduced by the return reproducinghead 21B. The reproducing signals from these heads 21A, 21B areamplified by reproducing amplifiers 22A, 22B, respectively, and suppliedto the selected terminals a, b of the change-over switch 26,respectively, through address separating circuits 23A, 23B,respectively. During forward direction reproduction, the switch 26 isset to the terminal a and only the reproduced signals from the addressseparating circuit 23A are supplied to the decoder 24 for decoding.These include signals which have been delayed and the signals aredelivered to the output terminal 25. The address separating circuits23A, 23B are used for extracting forward and return route addresses fromthe playback signals from the respective tracks 7A, 7B. The forward andreturn direction addresses are extracted in this manner and are comparedto each other so as to determine the relative signal magnitudes in theaddress comparing circuit 27. When the forward direction address isequal to or larger than the return direction address, the optimumreversing position signal is supplied to a system control circuit 38.The optimum reversing position is situated, for example, at the 14thblock playback position in the forward track 7A in the recording patternshown in FIG. 2. In response to the detection of the optimum reversingposition, the system control circuit 38 operates to reverse the taperunning direction and to move the changeover switch from terminal a toterminal b. Thus, during the return reproduction following the tapereversal, the playback signals from the return direction reproducinghead 21B are supplied via amplifier 22B through decoder 24 and aredecoded and supplied to the output terminal 25.

It should be noted that the magnetic tape 6 runs in the direction ofarrow A during reproduction in the forward direction so that the returndirection reproducing head 21B operates to scan the return directionrecording track in the opposite direction, and the return directionplayback signals are reproduced in reverse time order.

FIG. 5 is a block circuit diagram showing an example of the moredetailed construction of the basic circuit of the recording part shownin FIG. 1. In the present example, a random access memory 10 (RAM) isused as the delay element and the digital signals in block form aresequentially recorded on the magnetic tape.

In FIG. 5, the digital signals obtained from PCM audio signals aresupplied in chronological order in block form, and these input signalsare supplied to RAM 10 to delay the digital signals and they are writtenin associated addresses (write addresses). The digital signal data readfrom associated addresses (read addresses) of the delay RAM 10 aresupplied to a recording magnetic transducer head 5 through an encoder 11and a recording amplifier 4 and are recorded on the magnetic tape 6which is the magnetic recording medium.

A timing generator 12 in FIG. 5, supplies read/write control signals R/Wfor controlling reading from and writing into the RAM 10 during theentry of one block signals, and these control signals R/W are suppliedto the switching control terminals of a multiplexer 13 and to thedelaying RAM 10, respectively. The function of the multiplexer 13 is tomake a selection between the write address input WA and the read addressinput RA in accordance with the control signal R/W so as to send theselected output signal to an address input terminal of the RAM 10. Thewrite address WA is outputted from a write address counter 14 and theread address RA is outputted from a read address counter 15. To theclock input terminals CK of these counters 14, 15 there are suppliedclock pulses of the aforementioned block period from the timinggenerator 12. The read address counter 15 also operates to output inputaddress data from an address computing circuit 17 which have not beenaltered in response to commands from the system control circuit 16. Thecircuit 16 operates to control the reversal of the tape runningdirection in response to command signals for movement reversal, forexample, to the receipt of the tape end detection signals from a tapeend sensor 18 which are supplied to the control circuit 16. The circuit16 also sends out pulses to a load control terminal LD of the readaddress counter 15 and to control terminals of the address computingcircuit 17 for changing the read addresses before and after reversal andfor changing the time between the input and output of the delaying RAM10. Write addresses from the write address counter 14 are supplied tothe address computing circuit 17 for computing the post-reversal readaddresses. The control circuit 16 also activates a reversal markgenerator 19 responsive to input signals such as the aforementioned tapeend detection signals, and reversal mark signals are supplied from thegenerator 19 to an encoder 11. The function of the reversal markgenerator 19 is to produce the reversal mark signals which indicates theimpending movement reversing position, which reversal mark signals arerecorded on the tape along with the input signals. It is preferred thatthe return direction addresses be detected during forward directionreproduction since it requires a certain time to detect the reversalmark signals to be compared with the forward addresses.

Various forms of the end sensor 18 are known in the art, for example,those based on detection of the tape tension as the tape end isapproached, or on optical detection of the taut angle of the tape. Also,for sensing the tape leader at the tape end, it is known to detect thetransparent or reflective leader optically or to detect the metallicleader which causes changes in inductance or impedance at the electrodeterminal. It is also known to optically detect the through-hole formedin the tape.

The reversal mark signals are outputted from the reversal mark generator19 from the time of detection of the tape end by the end sensor 18 untilthe start of the mechanical tape movement reversal, and these signalsare supplied to the encoder 11. The reversal mark signals are recorded,along with the input signals, on the terminal portions of the forwardtrack 7A of the magnetic tape 6. For example, the reversal mark andinput signals are recorded in the seven blocks from the 9th to the 15thblocks indicated with small circles in FIG. 2. It should be noted thatthe timing or the time interval at which these reversal mark signals arerecorded may be controlled by the system control circuit 16. Forexample, after the movement reversal has been completed the reversalmark signals may be generated for a certain time (of the order ofseveral block periods) and can be recorded at the beginning portion ofthe return track 7B (for example, several blocks from the 12th blockshown in FIG. 2 towards left).

In the signal delaying RAM 10 of the circuit shown in FIG. 5, the inputsignals for one block are written into the associated write addressesdepending on the command of the write address WA, and the input signalsfor one block written in the associated read addresses are read outdepending on upon the commands of the read address RA. The one-blockrecording signals are arranged in a format as shown in FIG. 6 and areessentially composed of a block sync signal portion BS, a flag portionFLG which indicates various conditions, a block address portion BA, aninput signal data portion DATA, a parity data portion P and an errorcorrecting data portion CRCC, as viewed from the foremost position. TheRAM 10 is able to store at least the input signal data portion DATA ofthe block format in association with an indicating address, while otherportions of the format can be supplemented e.g. in the encoder 11. It ishowever preferred that, since the signal delaying operation is includedin the signal processing by the encoder, that the RAM in the encoder besimultaneously used as the signal delaying RAM 10.

For recording the reversal mark signals, one bit of the various statusflag portions FLG may be used as a reversal mark bit, in such a mannerthat the reversal mark bit always (excepting for the reversing position)becomes "0" for indicating other than the reversing position and becomes"1" for indicating the reversing position. Two or more bits may be usedso that a binary value is incremented or decremented as the tapeapproaches the reversing position.

In general, the aforementioned read address RA and the write address WAare indicated by a binary value with e.g. 8 bits. When a sequentialaccess is made to the addresses in the binary representation with theaid of e.g. a binary counter, all the addresses may be considered to thesequentially arranged on a circle as shown in FIGS. 7 to 9 by havingaccess to an all "0" address after having access to an all "1" address.For example, in case of an 8-bit address, addresses 0 to 255 can besequentially arranged in order with the address 0 arranged next to theaddress 255 form an endless loop.

FIG. 7 shows the changes of state of the read address RA and the writeaddress WA in the course of the forward direction with the magnetic tape6 running in the first direction A. Responsive to the count operation ofthe address counters 14, 15, the addresses RA, WA are moving at equalspeeds in the direction of an arrow mark C on a circumferencerepresentative of the address space of the RAM 10. The delay time T_(DA)for the forward direction recording is determined by the number ofaddresses included between the write address WA and the read address RA.One address of the RAM 10 specifies one block of the recording signaland the address is incremented by one for each block period T_(B), sothat, when the address difference (WA-RA) from the address WA to theaddress RA is, for example, n_(A), the delay time T_(DA) is equal ton_(A) T_(B).

FIG. 8 shows the state in which a reversal command signal is sent duringthe forward direction recording from the system control circuit 16 tothe tape running system responsive to, for example, the tape enddetection, that is, the state corresponding to the impending tapereversal. With a position P_(A) in the RAM address space specified bythe write address WA and a position Q_(A) in the RAM address spacespecified by the read address signals RA, the difference in the addressbetween these addresses P_(A) and Q_(A) is equal to n_(A) and the delaytime is equal to T_(DA) (=n_(A) T_(B)), as described hereinabove. Duringtape reversal, the write address WA continues to be moved in thedirection of the arrow C at a constant speed for sequentially writingthe input signals in the RAM 10 in the above described block sequence.There are, no limitations imposed on the read address RA, which mayremain stationary at the position Q_(A).

Upon the termination of the tape reversal, as shown in FIG. 9, the pointspecified by the write address WA is P_(B) which corresponds to a pointwhich has been advanced from the point P_(A) by a time T_(R) which isrequired for tape reversal. The point Q_(B) specified by the readaddress RA is at an address position which precedes the aforementionedpoint Q_(A). The read address RA and the write address WA are moved inthe direction of the arrow C at a speed equal to the pre-reversal speed.The delay time T_(DB) since the time of reading until the time ofwriting is equal to the product of the block period T_(B) and thedifference n_(B) (T_(DB=n) _(B) T_(B)) in the number of addresses fromWA to RA. It is necessary that the memory capacity of the RAM 10 and theread address RA immediately after the reversal be set so that thedifference in time T_(D) between the delay time T_(DB) for the returndirection recording following tape reversal and the delay time T_(DA)for forward direction recording (=T_(DB) -T_(DA)) be larger than theaforementioned time required for tape reversal T_(R) (T_(D) >T_(R)).Thus it is required that, on the circumference of FIG. 9 at a positioncorresponding to the RAM address space that, the position Q_(B) of theread address RA at the termination of the tape reversal be set so thatit is advanced in a direction which is opposite to the direction C, fromthe position Q_(B) of the read address RA at the time of the initiationof the tape reversal, and also such that it is ahead of the positionP_(B) of the write address WA in the direction C. Before and after thereversal operation, the input data written in the addresses from thepoint Q_(B) to the point Q_(A) is read out twice and is recorded twiceon both the forward direction track 7A and the return direction track7B.

In FIG. 10, there is shown in a block diagram a practical circuit bymeans of which the magnetic tape on which the recording has been made bythe signal recording method described in connection with FIG. 5 isreproduced with automatic movement reversal (auto-reverse).

Referring to FIG. 10, reciprocating recording has been made on themagnetic tape 6 with the aid of the recording device of FIG. 5 inaccordance with a recording pattern as shown by way of an exampleillustrated in FIG. 2. The signals recorded on the tape 6 are reproducedby the reproducing transducer heads 21A, 21B and are amplified by thereproducing amplifiers 22A, 22B and thence supplied to the delaying RAM30 through the reversal mark address separating circuits 23A, theaddress separating circuit 23B and the changeover switch 26. The signalsread out from RAM 30 appear at an output terminal 25 after passingthrough a decoder 24.

Each signal block read out from the reproducing transducer heads 21A,21B has the block format shown in FIG. 6. Thus, by sensing the blockunit on the basis of the block sync portion BS, the block addressportion BA and the reversal mark portion in the various status flags FLGin each block of the reproduced signal can be sequentially taken out atthe reversal mark/address separating circuit 23A and the addressseparating circuit 23B. The block address outputs from the separatingcircuits 23A, 23B are delivered as write address WA to the multiplexer31 through the changeover switch 28. The read addresses RA from the readaddress counter 32 are also introduced into the multiplexer 31, and theread addresses RA or the write addresses WA are occasionally selecteddepending upon the read/write control signal R/W from the timinggenerator 33 and are supplied to the address input terminal of the RAM30. Clock pulses are supplied from the timing generator 33 to the readaddress counter 32 at a constant block period so that the read addressRA appears as a signal sequentially incremented at said constant blockperiod. The read address RA from the read address counter 32 isdelivered to a positive input terminal of the subtractive circuit 34.The write address WA from the reversal mark/address separating circuit23A or the address separating circuit 23B is delivered to the negativeinput (subtracting input) terminal of the subtractive circuit 34 so thatthe difference in the addresses (RA-WA) is obtained from the subtractivecircuit 34. The subtractive output is delivered to the tape drivingmotor 37 through an offset supplementing circuit 35 and a servoamplifier 36. The reversal mark detection signals from the reversalmark/address separating circuit 23A is delivered to the system controlcircuit 38. The block addresses from the address separating circuits23A, 23B are compared in the address comparing circuit 27, and thedetection signal of the aforementioned optimum reversal position isdelivered to the system control circuit 38. Responsive to the reversalmark detection signal and the optimum reversal position detectionsignal, the system control circuit 38 operates to control the reversalof the tape running direction and to control the changeover switches 26,28. The switches 26, 28 are set to terminal a during forward directionreproduction and to terminal b during return direction reproduction.

Reference is had to FIGS. 11 to 13 for explaining the playback operationwith the auto-reverse function by means of the above describedreproducing circuit. It is assumed that, with the recording pattern onthe magnetic tape 6 as shown in FIG. 2, the operation of reversing therunning direction is effected during forward direction reproduction inthe first direction A at the 9th to 15th blocks and at such time thatthe reversal mark signal or the aforementioned optimum reversingposition have been detected, the tape is caused to run in the seconddirection after the predetermined time T_(R) so as to start the returnreproduction. In FIGS. 11 to 13, the address space of the signaldelaying RAM 30 is indicated by the circumference in the same manner asin FIGS. 7 to 9 described hereinabove.

During forward reproduction, the read address RA and the write addressWA are travelling in the direction C on the circumference correspondingto the address space as shown for example in FIG. 11. The speed ofmovement of the read address RA (address increment speed) is maintainedconstant by the clock signals supplied from the timing generator 33 ofFIG. 10 to the read address counter 32, whereas the speed of movement ofthe write address WA (address increment speed) is changed with minorfluctuations in the tape running speed because the write address makesdirect use of the address portions of the respective blocks in thereproducing signals. It should however be noted that the position of theread address RA relative to the write address WA is automaticallycontrolled so that a constant offset T_(off) is maintained by the tapedriving servo system including the subtractive circuit 34 and theoffsetting circuit 35. The address offset T_(off) is determined by theoffset amount of the offsetting circuit 35.

Next, at the time point where the aforementioned movement reversal isstarted responsive to the detection of the optimum reversing position,the write address WA ceases to be moved and writing is discontinued,whereas the read address RA continues its movement at the aforementionedconstant speed, as shown in FIG. 12. This is because the tape becomessubstantially stationary and no playback signals are available duringtape reversal. The position of the write address WA in the RAM addressspace at the time when the movement reversal is started is indicated asU_(A) and the time of the read address RA is indicated as V_(A).

At the time when the movement reversal is terminated, the magnetic tape6 is started to run in the second direction so as to start thereproduction of the recording on the second or return track 7B and thewrite address WA is started to run in the direction C, as shown in FIG.13. The position U_(B) of the write address WA at the instant thereversal is terminated is determined by the block address obtained forthe first time during the reproduction in the second or returndirection. When the reversal has occurred at the aforementioned optimumreversing position, the position U_(B) is substantially coincident withthe position U_(A) of the start of the reversal or slightly shiftedtherefrom in a direction which is opposite to the direction C. Theposition V_(B) of the read address RA at the time of reversal iscompleted is advanced in the direction C from the position V_(A) by thetime required for movement reversal T_(R). The capacity of the delay RAM30 must be selected so that the position V_(B) at the instant of thereversal termination does not exceed the aforementioned position U_(B).

After termination of the movement reversal and the start of the returndirection reproduction, the tape speed is increased by the operation ofthe tape running servo system including the subtractive circuit 34 andthe offsetting circuit 35 so that the movement of the write address WAin the direction C is accelerated and the write address becomes close tothe read address RA. The distance between the addresses RA and WA isultimately servo-controlled and approximately stabilized to the constantsteady-state offset T_(off), as shown in FIG. 11, so that the addressesRA and WA are moved in direction C at the approximately equal speed.

Thus, no omission of the signals written into the delaying RAM 30 takesplace before or after tape reversal, while the read address RA is alwaysmoved in the direction C at a constant speed so as to permit reading ofthe transient signals. Also, in the steady-state forward or returnreproduction condition shown in FIG. 11, the T_(off) intervals beforeand after the write address WA represent a so-called jitter margin forcompensating for fluctuations caused during tape running, whereas theremaining interval T_(M) represents the reversal margin for compensatingfor fluctuations caused by tape reversal.

It should be noted that, while the block address of e.g. 8 bits issufficient for identifying 256 blocks, the number of the blocks from thebeginning until the end of the magnetic tape in the running directionthereof is extremely large so that the same block address will appearrepeatedly at a constant period during tape running. It is thereforepreferred that not only the comparison of the block addresses for theforward and return directions but also that the reversal marks are usedso that the detection of the optimum reversing position by means of theaddress comparison output is validated only when the reversal marksignals are detected at the position where the movement reversal isrequired, as at the tape end. In the above embodiment, this is effectedat the system control circuit 38 by taking the logical product (AND),for example, between the reversal mark detection signal and the optimumreversing position detection signal. Alternatively, the returnreproducing head 21B is activated only when the reversal mark detectionsignal is obtained during the forward reproduction for reading out thereturn route addresses.

In the above described embodiment of the present invention, the timerequired for reversal between the forward movement and the returnmovement is compensated during the recording by the delay caused in theinput signals by making use of the RAM 10 as an input signal delay meansso that continuous trouble-free reverse recording is achieved withoutomission of the input signals recorded on the magnetic tape 6.

For the reproduction of the thus recorded magnetic tape 6, data aresequentially written into the RAM 30 which is the signal delay means inassociation with the addresses of the playback signals obtained fromreproducing head 21 and the reading from the RAM is effected continuallywith the constant clock timing so that continuous trouble-free reverseplayback is achieved without omission of the playback output signals.This is made possible by the fact that the playback signal datacorresponding to the time required for tape reversal is stored twice toprovide a reversal margin during the steady-state reproduction (at leastunder the impending movement reversal conditions).

According to an embodiment, the movement reversal is effected at theextreme position during reproduction where the signal omission is stillprevented from occurring, so that the reversal margin is reduced and thememory capacity of the delay RAM 30 is minimized. In addition thereto,because of the smaller memory capacity, the time that elapses since thestart of reproduction until the actual sound reproduction is alsoreduced.

Although the present invention has been described hereinabove withrespect to an application thereof to a stationary head type auto-reversetape recorder, the present invention can also be applied to a rotaryhead type auto-reverse tape recorder as well. For example, FIG. 14 showsa reciprocating recording pattern on the magnetic tape 6 with the use ofthe rotary recording head. With the tape running in the direction A forforward direction recording, plural helical recording tracks 7A aresequentially formed in the direction opposite to the direction A and,with the tape running in the direction B for return direction recording,plural recording tracks 7B are sequentially recorded. In such case, anumber of blocks, e.g. hundreds of blocks are formed as one frame oneach helical recording track 7. One of these blocks may be used as acontrol block CTL in which may be included the aforementioned reversalmark information or the tracks so that it increases the error in thedetection of the aforementioned optimum position.

With such rotary head type auto-reverse device, an axial error isincreased by a factor of cot θ, where θ represents an angle ofinclination of the recording tracks so that it is increased to a largererror in the running direction. Thus it is essential that the movementreversal position be determined with a high accuracy. Therefore, thepresent invention can be applied most effectively to such rotary typerecording devices.

It is to be noted that the present invention is not limited to the abovedescribed embodiments, but may also be applied to the case of arranginginput signals in a block form and including the reversal mark or addressinformation etc. in each block, wherein the frequency division system orthe system providing independent signal data tracks and the controltracks can be adopted besides the time division system in which thesignal data portion, reversal mark or the address information arearranged on the time axis.

According to the signal recording apparatus of the present invention,the input signals temporarily preceding the input signals recorded onthe medium immediately before the tape reversal are recorded after thetime immediately following the tape reversal so that the input signalscan be recorded on the recording medium without signal omission thusproviding for a continuous trouble-free signal recording.

In addition thereto, according to the signal recording and reproducingapparatus of the present invention, in the reproduction of the recordingmedium on which recording has been made by the above described signalrecording system, the playback signals from the playback or reproducinghead are taken out at least immediately before the movement reversalwith a delay longer than the time required for movement reversal so thatthe signals can be taken out continuously from the delay means duringreversal, thus providing for a continuous trouble-free reversereproduction.

Also, the information concerning the return direction can be obtainedduring forward direction reproduction so that movement reversal can beeffected at a position necessary and sufficient for auto-reversereproduction, while the capacity of the signal delay memory adapted forpreventing the playback signal omission may be reduced.

I claim:
 1. A signal recording and reproducing apparatus wherein, afterat least one of the recording head and the recording medium has made arelative movement in a first direction, said recording medium is movedin a second direction opposite to said first direction forreciprocatingly recording input signals, and wherein said recordingmedium is caused to reciprocatingly travel in said first and seconddirections for reproducing the recording with a reproducing head,characterized in that, during recording, means are provided forsupplying said input signals to said recording head with a delay, thedelay of the input signals during running in said second direction beinglonger than the delay of the input signals during running in said firstdirection and the difference between said delays selected so as to belonger than the time required for movement reversal from said firstdirection to said second direction; and during reproduction, means areprovided for delaying the reproduced signals from said reproducing head,with delay of the reproduced signals prior to movement reversal selectedso as to be longer than the delay of the reproduced signals aftermovement reversal, and the output signal supplied from said delay meanscomprises a continuous output signals, wherein the signals arereciprocatingly recorded on the recording medium, characterized in thatreversal mark signals indicative of the reversal are recorded on saidrecording medium in the vicinity of the reversal position along withsaid input signals.
 2. A signal recording apparatus wherein, after atleast one of the recording head and the recording medium has made arelative movement in a first direction, said recording medium is movedin a second direction opposite to said first direction forreciprocatingly recording input signals on said recording medium,characterized in that means are provided for supplying said inputsignals to said recording head with a delay, and the amount of delay ofthe input signals during running in said second direction is set to belonger than the delay of the input signals during running in said firstdirection and the difference between these delays is selected to belonger than the time required for reversal of said recording medium fromsaid first direction to said second direction, wherein the signals arereciprocatingly recorded on the recording medium, characterized in thatreversal mark signals indicative of the reversal are recorded on saidrecording medium in the vicinity of the reversal position along withsaid input signals.
 3. A signal recording and reproducing apparatuscharacterized in that the input signals and the addresses correspondingthereto are reciprocatingly recorded on a recording medium, the thusrecorded signals are read out in both the forward and return directionsduring forward reproduction, and the thus read out forward directionaddresses and the return direction addresses are compared to each otherso as to determine the movement reversal position and to assumecontinuous uninterrupted data during reversal of the magnetic medium.